Plastic compression technology and mold design of HDPE closures for beverage bottles

LUO Da， LIANG Wen-jie
（Hangzhou Wahaha Group Co.，Ltd.， Hangzhou 311215， China）

Abstract： Aiming that the sliding friction structure in the inner lining sleeve and the screw thread core of the traditional beverage bottle cap pressing forming mould caused the friction surfaces to nap，blocking，easy wear etc.， the rolling friction technology with wear small，small movement resistance was applied to the compression molding mould. Whether a rolling member was inserted between the inner bushing and the screw thread core in place of the original sliding friction was discussed.The relationship between the sliding friction，rolling friction and the wear speed was established，a ball retainer ring was added between the inner bushing and the screw thread core. The original sliding friction was changed into the rolling friction，thereby reducing wear and improving the life of the mould. The mould structure，manufacturing technology，economic benefits etc. were evaluated on the mould life and the cap quality. New structure of compression molding mold was designed and manufactured，and the long term test was developed on the original cap making machine. Research results show that，the mould wear is very little. Cap quality is better than before. The mould service life is raised one time above compared with the conventional compression molding mould.
Key words： HDPE beverage bottle cap； compression molding； mold design